1. Field
Exemplary embodiments relate to a surface acoustic wave (“SAW”) sensor and a sensing method using a SAW.
2. Description of the Related Art
In a SAW sensor using a piezoelectric material, a SAW may be created when a radio frequency (“RF”) signal is applied to an input electrode. If a target substance is bonded to the surface of the SAW sensor, the surface mass of the SAW sensor may change. The SAW may be subjected to a change due to the weight of the target substance on the SAW sensor. The SAW may be converted again into an electrical signal and outputted from an output electrode. After the SAW is converted back into an electrical signal, the SAW sensor may detect a change in the output signal caused by the target substance to sense the substance bonded to the sensor.
One technique used for applying a signal to an electrode of the SAW sensor for generating a SAW makes use of oscillation which applies an output signal output from a SAW sensor as an input signal back to the SAW sensor. This technique requires a gap between an input electrode and an output electrode that is relatively narrow and every sensor oscillates independently when a plurality of SAW sensors is employed. Another technique adopts a network analyzer to generate a signal of a predetermined frequency on the outside of a SAW sensor and applies the signal to the SAW sensor. The signal applied by the network analyzer may have a frequency separation of several kHz or greater.